When the current flowing in a conductor for each of three phases, e.g., A-phase, B-phase, and C-phase, is measured, the voltage generated by the current flowing in the conductors for the other phases is superimposed on an air-cored coil and this affects the accuracy of the output from the current detection device. Therefore, for conventional current detection devices, for example, a technology has been disclosed in which a correction process is performed that takes the voltage superimposed due to other phase currents into consideration and the result of the correction process is output as the current flowing in each phase conductor (for example, Patent Literature 1).